Author: Ms. Neha Goel
Volume: 01
First Online: 31 August 2024
Pages: 49-57
DOI:

Adrenergic neurotransmitters, primarily catecholamines like dopamine, norepinephrine, and epinephrine, play vital roles in the body’s response to stress and regulation of various physiological functions. The biosynthesis of catecholamines begins with the amino acid tyrosine, which is converted into LDOPA by the enzyme tyrosine hydroxylase. L-DOPA is then decarboxylated to form dopamine, which can be further hydroxylated to produce norepinephrine and finally methylated to form epinephrine. The catabolism of catecholamines involves enzymes like monoamine oxidase (MAO) and catechol-Omethyltransferase (COMT),
which break down these neurotransmitters into inactive metabolites excreted in the urine. Adrenergic receptors, classified into alpha and beta types, mediate the effects of catecholamines. Alpha receptors (α1 and α2) are primarily found in smooth muscles and blood vessels, where they regulate vasoconstriction and blood pressure. Beta receptors (β1, β2, and β3) are distributed in the heart, lungs, and adipose tissue, with β1 receptors increasing heart rate and contractility, β2 receptors causing bronchodilation and vasodilation, and β3 receptors involved in lipolysis. The precise distribution and function of these receptors enable the fine- tuning of physiological responses, highlighting the intricate balance maintained by the adrenergic system in maintaining homeostasis.